Step 1: Understanding the relationship between kinetic energy and droplet size.
The kinetic energy (E) of a raindrop is proportional to the mass of the droplet and the square of its velocity. Since the mass of a raindrop is proportional to the volume, and volume is proportional to \(D^3\) (where D is the diameter), the kinetic energy increases with the fourth power of the droplet diameter, \( E \propto D^4 \).
Step 2: Evaluating the options.
Option (A) is incorrect because \( E \propto D^{1/2} \) would imply a square root relationship between energy and droplet size, which is not correct.
Option (B) is incorrect because \( E \propto D^2 \) implies a quadratic relationship, which does not apply to the kinetic energy of raindrops.
Option (C) is incorrect because \( E \propto D^3 \) implies that energy increases with the cube of the droplet size, which is not the correct relationship.
Option (D) is correct because the kinetic energy of a raindrop is proportional to the fourth power of its diameter, as both mass and velocity depend on the size of the droplet.